This invention relates to hydroponic planters. It is particularly concerned with such a planter which facilitates giving plants growing in the planter proper light, water, nutrients, and aeration.
Growing plants in a planter has long required considerable care and skill. Too often, house plants receive too little or too much care, and they succumb. Many attempts have been made to simplify the care of houseplants, but none has been simple enough or effective enough to provide a widely acceptable system.
Hydroponic plant systems have certain advantages over soil-based systems, but even they have not proven adequate to the simple growing of houseplants over long periods of time.
When growing plants in a hydroponic setting, it is very important to have the plant growing in an area where it is not too dark and to have the level of the liquid nutrients in the planter not exceed a maximum level, nor should the plants be dry for too long. If overwatering occurs, the plant will die from root rot. Allowing the roots of the plant to be dry for too long results in dehydration and starving the plant. Thus, an accurate method of determining liquid levels in the planter is necessary.
The plant industry currently uses hand-held, electronically operated gauges to determine appropriate light levels for a given plant. These gauges are expensive and cumbersome.
Light gauges have sometimes been associated with or combined with a bimetallic operated moisture indicator, but these indicators are useless in any form of hydroponics. Generally, the water/nutrient level indicators used in the field of hydroponics have been the dipstick and float types as exemplified by U.S. Pat. No. 2,799,089 Banker, U.S. Pat. No. 3,483,656 Baumann, U.S. Pat. No. 3,739,524 Rose, U.S. Pat. No. 4,055,991 Bridwell, U.S. Pat. No. 4,171,593 Bigglestone, U.S. Pat. No. 4,270,309 Baumann and D257,529 Raap. Their disadvantages become apparent during use: the float is easily clogged by salt buildup, root fines, or live roots growing into the slots in the meter, and gives false readings which result in the death of the plants. In addition, the float and the rod displace a certain amount of liquid, so even when the meter reads empty, there can be over one-half inch of water/nutrient remaining in the system. Because plant roots require a periodic drying for their health, these meters lead to frequent overwatering of the plant and death of the plants. Windows in the sides of the pot have also been tried. However, algae buildup on the windows makes them unreadable in short order, and the windows tend to leak after some handling.
Many systems have been developed over the years to help alleviate the problems with over- and underwatering, diseases, pests and human error. To help eliminate water spills, the plant saucer was developed and soon began to be used as a watering device, which brought on the development of simple self-watering devices and even more controlled self-waterers utilizing wicks or capillary action through porous materials as exemplified by such patents as U.S. Pat. No. 2,406,439 Pratt, U.S. Pat. No. 3,137,096 Hopkins, U.S. Pat. No. 3,739,524 Rose, U.S. Pat. No. 4,001,967 Swift, U.S. Pat. No. 4,083,146 Brankovic, U.S. Pat. No. 4,106,235 Smith, U.S. Pat. No. 4,143,487 Hollwarth, U.S. Pat. No. 4,10,342 Dryer, U.S. Pat. No. 4,216,623 Silver, U.S. Pat. No. 4,344,251 Edling, U.S. Pat. No. 4,356,665 De Oliveira, and U.S. Pat. No. 4,557,070 Oyama. Most of these devices did not alleviate the problems of over- and underwatering.
Overwatering and drainage have been such a large problem that numerous patents have been issued on simple pots with improved drainage or more complex collapsible pots with aeration features such as depicted in U.S. Pat. No. 4,100,699 Skaife and U.S. Pat. No. 4,173,097 Staby.
With hydroponics and the advent of true hydroculture techniques reaching the public, many attempts to use hydroculture techniques with soil plants have been made, as shown by U.S. Pat. No. 3,534,498 Herrli, which is now considered a capillary wick waterer. Hydroculture in its present form has been around for quite some time with little change in the growing medium, the aeration methods, or the way in which liquid levels are determined, as suggested by U.S. Pat. Nos. 3,483,656, 4,270,309 Baumann, and U.S. Pat. No. 4,663,884 Zeischegg. As exemplified by these patents, such hydroponic systems have frequently used an open-topped outer container for holding liquid, an open-topped inner container for holding an inert growing medium, and a plant in the medium. The inner container includes openings at its lower end to allow liquid to enter the growing medium and to drain from it.
The growing medium used in hydroponic systems has always been what was readily available locally or could be obtained in large quantities, cheaply. In many cases perlite or vermiculite has been tried for hydroculture but the norm is expanded clay pellets, most of which are imported from European countries. Imported expanded clay, although claimed to be the perfect medium, does slake in water and eventually breaks down to chalk, much like the decay of used brick. The liquid retention properties of clay pellets are acceptable, but their various manufactured shapes have led to many problems. The round substrate although non-damaging to roots never lends good anchorage to the root ball, and as the plant's roots grow and expand, capillary action of this substrate begins to decay. The peanut shaped substrate gives better anchorage to the roots but slakes rapidly, clogging root hairs and killing the plant. Slight compaction and sharp edges tend to cut or smother the plant's roots. Expanded shale, commonly called Haydite, contains chemicals which slake into the water, poisoning the system and eventually killing the plant. Sodium and sulfur are the most notable of these chemicals.